1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method, and more particularly to an intermediate transfer type image forming apparatus and method therefor, by which an image is formed on a recording medium by transferring an image formed on an intermediate transfer body to the recording medium.
2. Description of the Related Art
Inkjet recording apparatuses are known which use a so-called intermediate transfer system, in which an image is formed on an intermediate transfer body by a recording head (inkjet head), and the image formed on the intermediate transfer body is then transferred to a recording medium. In a recording apparatus in the related art, it is difficult to achieve high image quality as well as achieving good transfer characteristics on the intermediate transfer body. This is because intermediate transfer bodies that have good transfer and separation characteristics are often made from materials that basically have low surface energy and high liquid-repelling properties, and therefore liquid flows are liable to arise on the intermediate transfer body, and hence image quality is liable to decline. In view of these circumstances, various methods have been proposed in order to achieve good image quality on intermediate transfer bodies.
For example, Japanese Patent Application Publication Nos. 2005-14255 and 2005-14256 disclose methods for improving the surface of the intermediate transfer body. In Japanese Patent Application Publication No. 2005-14255, surface improvement is carried out by plasma processing or surfactant deposition processing on an intermediate transfer body having at least one surface made of a fluorocarbon compound or a silicone compound. In Japanese Patent Application Publication No. 2005-14256, surface improvement is carried out by applying energy to an intermediate transfer body with a surface having releasing properties.
Japanese Patent Application Publication No. 2002-370441 discloses a method which uses two types of liquid, namely a first liquid that contains a solvent-insoluble material, such as coloring material, and a second liquid that is reactive with respect to the first liquid and forms an aggregate. According to this method, when the second liquid is deposited onto an intermediate transfer body by a recording head and a first liquid is subsequently deposited onto the intermediate transfer body, an image free of bleeding and feathering is formed on the intermediate transfer body, and the image formed on the intermediate transfer body is then transferred to the recording medium, by supplying the second liquid at a smaller liquid deposition volume than the liquid deposition volume of the first liquid.
Japanese Patent Application Publication No. 2004-114675 discloses a method in which a first material that improves the wetting characteristics of an intermediate transfer body is deposited onto the intermediate transfer body, a second material for reducing the fluidity of the ink is deposited onto the intermediate transfer body, and ink is ejected from a recording head, thereby forming an image on the intermediate transfer body.
However, the methods disclosed in Japanese Patent Application Publication Nos. 2005-14255 and 2005-14256 are problematic in that they place a large load on the system. Moreover, although the method disclosed in Japanese Patent Application Publication No. 2002-370441 is valuable in achieving high image quality on an intermediate transfer body in a relatively low-speed system; in the case of a high-speed system, the time from the mixing of the first liquid and the second liquid on the intermediate transfer body until the transfer action is extremely short, and therefore, a sufficient reaction is not achieved, and it has been observed that the dots are disturbed during transfer and residual material is left on the intermediate transfer body after transfer. Consequently, there is a problem in that residual material on the intermediate transfer body must be removed and this places an extremely large burden on the cleaning of the intermediate transfer body surface. Furthermore, the method disclosed in Japanese Patent Application Publication No. 2004-114675 uses a process based on three materials, and system characteristics are poor.